1. Field of the Invention
This invention relates to tamper indicating closures for application to a container neck and more particularly to a tamper indicating closure in which separation of a tamper indicating band upon unthreading of the closure indicates tampering or prior removal but in which the tamper indicating band remains tethered to the cap for removal of the cap and tamper indicating band as a unit from the container.
2. Description of Related Art
A common form of tamper indicating closure incorporates a combined cap and tamper indicating band and uses a stop device for restraining axial movement of the tamper indicating band on the container neck. An inwardly directed lip or bead on the tamper indicating band seats below and acts with an outwardly directed bead or flange on the container neck. In the process of threading the closure on the container neck, the bead on the tamper indicating band snaps below the flange on the container neck. During unthreading, the band can rotate but is restrained against axial movement by the container flange so that frangible webs formed between the bottom of the cap and the top of the tamper indicating band are fractured primarily in tension. The broken webs give evidence of tampering and permit the unthreading of the cap from the container to give access to the contents of the container. It often is desirable to remove the tamper indicating ring from the container and provisions have been made for facilitating such removal either manually or in response to axial displacement of the cap relative to the container after the frangible webs between the cap and tamper indicating band have been fractured. In some such arrangements an axial line of weakening is provided to permit breaking or separation of the ring for removal and in other structures provision has been made for making one of the webs attaching the tamper indicating band to the cap stronger than the remaining webs so that upon removal of the cap all except the strong web break and permit removal of the cap and tamper indicating band as a unit on the container.
With closures in which the band remains attached to the cap by a single web or tether, the forces required for opening a container are not constant and are unpredictable because the webs between the tamper indicating band and cap do not break as intended, particularly those webs adjacent to the permanent web or tether. This results in the requirement for a greater opening force than intended to remove the tamper indicating band together with the cap from the closure.